Charging of an electric vehicle fleet

ABSTRACT

A method for controlling the charging of multiple electric vehicles operating in a geographic area may include inputting a tariff schedule into a control system. The tariff schedule may identify the cost of energy at different times in the geographic area. The method may also include receiving data from the multiple electric vehicles. The data may include at least the state of charge of the vehicle. The method may further include sending instructions to at least one vehicle of the multiple electric vehicles. The instructions may include directives on charging based at least on the tariff schedule and the received data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/309,560 filed on Jun. 19, 2014, which is incorporated by reference inits entirely herein.

TECHNICAL FIELD

The current disclosure relates to systems and methods of charging afleet of electric vehicles. In particular, the current disclosurerelates to a control system that controls the charging of electricvehicles of a fleet based on prevailing utility rates and the existingcharge in the vehicles.

BACKGROUND

An electric vehicle (EV), also referred to as an electric drive vehicle,uses an electric motor (or traction motor) for propulsion. Electricvehicles may include all-electric vehicles where the electric motor isthe sole source of power, and hybrid electric vehicles that include anauxiliary power source in addition to the electric motor. In an electricvehicle, energy may be stored in one or more batteries (located in theelectric vehicle) to power the electric motor. When the stored energydecreases, the batteries may be charged (or recharged) by connecting thevehicle to an external power supply. Although the current disclosure isapplicable, without limitations, to any type of electric vehicle, anexemplary case of an electric bus will be described to illustrate thefeatures of the disclosed system.

For a given weight of the bus, the number, chemistry, and architectureof the battery assembly may determine the distance the bus can travelbetween recharges (range) and the time it takes to recharge thebatteries (recharge time). For some applications, (for example, transitbuses) where quick charging is important, fast-charge battery systemsmay be employed. Fast-charge batteries may store a relatively smallamount of charge, but may be charged to substantially full capacityquickly. Battery system architecture may also allow fast charging ofnon-fast charge batteries. Some exemplary fast-charge battery systemssuitable for an electric bus are described in commonly assigned U.S.Pat. No. 8,453,773 which is incorporated herein by reference in itsentirety.

Because the range of a fast-charge electric bus is low, these buses aretypically recharged along its route. In some applications, chargingstations may be provided at a bus stop or another layover location torecharge the bus without inconveniencing passengers. At these chargingstations, the electric bus couples with an arm or other mechanism of thecharging station to direct external electric power to the bus torecharge the batteries. Typically, the cost of energy in a geographicarea (city, county, etc.) varies as a function of, among other factors,the season (summer, winter, etc.), time of day (peak time, off-peaktime, etc.), the rate of energy consumption (power), etc. When a fleetof electric buses operate in the area, energy cost may be a substantialportion of the total operating cost of the buses. Significant savings inenergy cost may be achieved by controlling the recharging of the busesin the fleet based on the energy rates and the state of charge of allthe buses in the fleet.

SUMMARY

Embodiments of the present disclosure relate to, among other things,systems and methods for controlling the charging of one or more electricvehicles. Each of the embodiments disclosed herein may include one ormore of the features described in connection with any of the otherdisclosed embodiments.

In one embodiment, a method for controlling the charging of multipleelectric vehicles operating in a geographic area using a control systemis disclosed. The method may include inputting a tariff schedule intothe control system. The tariff schedule may identify the cost of energyat different times in the geographic area. The method may also includereceiving, using the control system, data from the multiple electricvehicles. The data may include at least the state of charge of thevehicle. The method may also include sending instructions from thecontrol system to at least one vehicle of the multiple electricvehicles. The instructions may include directives on charging based atleast on the tariff schedule and the received data.

In another embodiment, a method of controlling the charging of a fleetof electric buses using a control system is disclosed. The method mayinclude inputting a tariff schedule into the control system. The tariffschedule may identify the cost of energy at different times. The methodmay also include receiving using the control system, data from aplurality of electric buses of the fleet. The data may include at leastthe state of charge of the plurality of electric buses. The method mayfurther include receiving using the control system, data related tocharging from one or more charging stations. The one or more chargingstations may be configured to charge the fleet of electric buses. Themethod may additionally include sending instructions from the controlsystem to at least one electric bus of the plurality of electric buses.The instructions may include directives related to charging based on atleast the tariff schedule and the received data from the plurality ofelectric buses.

In yet another embodiment, control system for controlling the chargingof a fleet of electric vehicles operating in a geographic area isdisclosed. The control system may include a computer system configuredto receive a tariff schedule. The tariff schedule may identify the costof energy at different times in the geographic area. The control systemmay also include a receiver configured to wirelessly receive datarelated to state of charge from multiple vehicles of the fleet ofelectric vehicles, and a processor configured to determine a chargingstrategy based on at least the tariff schedule and the received data.The control system may further include a transmitter adapted towirelessly transmit directives based on the determined charging strategyto at least one vehicle of the multiple vehicles.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of thepresent disclosure and together with the description, serve to explainthe principles of the disclosure.

FIG. 1 is a schematic illustration of a fleet of electric busesoperating in a geographic area;

FIG. 2A is an illustration of an exemplary control system that controlsthe charging of the electric buses of FIG. 1;

FIG. 2B is an illustration of the data sent to and from the controlsystem of FIG. 2A;

FIG. 3A is a flow chart that illustrates an exemplary operation ofcontrol system of FIG. 2A; and

FIG. 3B is a flow chart that illustrates another exemplary operation ofcontrol system of FIG. 2A.

DETAILED DESCRIPTION

The present disclosure describes a control system and a method ofcontrolling the charging of a fleet of electric buses to reduce utilitycost. While principles of the current disclosure are described withreference to an electric bus, it should be understood that thedisclosure is not limited thereto. Rather, the systems and methods ofthe present disclosure may be used to control the charging of any fleetof electric vehicles (taxis, etc.).

FIG. 1 is a schematic illustration of a fleet of electric buses 10operating along several routes 20 in a geographic area 100. Geographicarea 100 may include any area (airport, university campus, city, town,county, etc.) that can be serviced by a fleet of electric buses 10. Thefleet may include any number of electric buses 10. The fleet of buses 10may be operated by an authority 50 (transport authority, airportauthority, metro authority, etc.). One or more charging stations 30 maybe positioned along the different routes 20 to charge the buses 10 thatoperate on these routes 20. The charging stations 30 may be coupled toan electric grid that is supplied with energy (electricity) by a utilitycompany 40 that services the geographic area 100. When a bus 10 pulls upto a charging station 30, an interconnection mechanism of the chargingstation 30 couples with charging electrodes of the bus 10 to charge thebatteries of the bus 10. After charging the batteries to a desiredlevel, the bus 10 decouples from the interconnection mechanism andproceeds along its route 20. When the charge of the bus 10 decreasesbelow a predetermined value, the bus 10 pulls into the same or adifferent charging station 30 to get recharged. The charging stations 30may be positioned such that they service the buses 10 operating onseveral different routes 20.

Electric bus 10 may include a charging interface that couples with theinterconnection mechanism of the charging station 30 to transferelectric power to the batteries. Without limitation, the bus 10 mayinclude any type of charging interface that is adapted to couple withthe interconnection mechanism. In some embodiments, the charginginterface may be provided on the roof or another external surface of thebus 10. As the bus 10 stops at the charging station 30, theinterconnection mechanism may advance towards (in some embodiments,swing over and descend towards) and couple with the charging interfaceon the roof to charge the bus 10. Some possible embodiments of charginginterfaces and charging stations 30 are described in commonly-assignedpatents/applications: U.S. Pat. No. 8,324,858; and InternationalApplication Publication Nos. WO/2011/079215, WO/2011/079215, andWO/2011/139680 which are incorporated by reference in their entiretyherein.

In some embodiments, bus 10 may also include an on-board charging deviceto charge the batteries. The on-board charging device may include anauxiliary power generation device (such as, an internal combustionengine or a fuel cell) that generates supplemental power to charge thebatteries when desired (such as when the bus is not close to a chargingstation 30). In some embodiments, one or more of the charging stations30 may include an energy storage device 35 (capacitor, battery, etc.)electrically coupled thereto. Energy from the electric grid may be usedto charge the energy storage device 35 when the energy cost is lower,and this stored energy may be used to charge a bus 10 when the energycost is higher. Some possible embodiments of such energy storage devicesare described in commonly-assigned U.S. Provisional Patent ApplicationNo. 61/876,698 (titled Methods and Systems for Electric VehicleCharging) filed Sep. 11, 2013, which is incorporated by reference in itsentirety herein.

The utility company 40 may charge the authority 50 for the energyconsumed in charging the buses 10 based on a prevailing tariff schedule.The tariff schedule documents the cost per unit of electricity (forexample, $/kilo Watt) as a function of several factors. These factorsmay vary with the geographic area 100, and often includes variables suchas the season, time of use, rate of energy consumption, total energyconsumed, voltage, etc. Typically, energy cost is higher when the demandfor energy is higher (for example, Summer months, and times between 8AM-10 AM, 4 PM-6 PM, etc.) and lower when the demand is lower (forexample, Winter months, and at times between 10 AM-4 PM and 6 PM-8 AM).For a commercial consumer, the energy cost may follow a tiered approach.That is, the energy cost may change with the total power consumed. Forexample, total power consumption (per billing cycle) between 20 kiloWatts (kW) and 1 Mega Watt (MW) may be charged at a first rate, between1-50 MW may be charged at a second rate, and above 50 MW may be chargedat a third rate. The energy cost may also change as a function of therate at which energy is consumed. For example, the cost for 100 kWhr ofenergy may be higher if this amount of energy were consumed in one unitof time (unit of time=1 minute, 15 minutes, 30 minutes, etc.) than if itwere consumed over a longer time period (for example, in two units oftime). The utility company 40 may periodically revise the tariffschedule and communicate this revised schedule to authority 50 and otherconsumers. The tariff schedule may be digitally transmitted to, or apaper copy may be mailed to, the authority 50.

The authority 50 may operate a control system 60 that controls thecharging of the buses 10 based upon the tariff schedule. FIG. 2Aschematically illustrates the control system 60 that controls thecharging of the electric buses 10 operating in geographic area 100. Thecontrol system 60 may be positioned at any location (or multiplelocations) and include one or more computer systems (or connectedelectronic devices) networked together over a wired or wireless network.In some embodiments, control system 60 may reside in one or morecomputer servers in the offices of the authority 50. In someembodiments, the control system 60 may be located at a charging station30 or at another remote site. The control system 60 may be configured toreceive data from, among others, the buses 10, charging stations 30, theutility company 40, and the authority 50. The control system 60 may alsobe configured to store data, perform computations, and relay data and/orinstructions to the buses 10 and the charging stations 30. The controlsystem 60 may be configured to receive data wirelessly and/or over awired network. The control system 60 may also include input devices(such as, for example, key boards, disk/CD/DVD readers, memory cardreaders, etc.) configured to input data into the control system 60, andoutput devices (display devices, printers, disk/CD/DVD/memory cardwriters) configured to output data and information. The control system60 may also be configured to store data 62 and other information, andperform computations on the stored and received data.

The data 62 stored in the control system 60 may include the prevailingtariff schedule in geographic area 100. Data 62 may also include, amongothers, information regarding the routes 20, buses 20, drivers, and thepassengers. Information regarding the routes 20 may include GPSlocations of the different routes 20, bus schedules (bus times alongdifferent routes), distance between stops along the route 20, locationof charging stations 30 along the routes 20, etc. Information regardingthe buses 10 may include bus identifying information, expected energyconsumption of different buses (for example, based upon historic energyconsumption (miles/KWhr) data, the age, and state of repair of the bus),etc. Information regarding the drivers may include the driving habits ofthe drivers based on historical data. And, information regarding thepassengers may include historical data on the expected number ofpassengers at different stops along a route 20 at different times.

In some embodiments, the data 62 stored in the control system 60 mayinclude a default charging schedule for the buses 10. That is, based oninformation of the route 20 and the buses 10 that operate on the route20, the control system 60 may determine a default charging schedule forthe buses 10. The default charging schedule may be any schedule thatidentifies when each bus 10 in the fleet will be charged. In someembodiments, the default charging schedule may include charging the bus10 at the beginning or the completion of a route 20. That is, a bus 10operating on a repeated fixed route may charge at a charging station atthe beginning or the end of the route. In some embodiments, the defaultcharging schedule may include charging a bus 10 at every chargingstation 30 it passes by. In some embodiments, the control system 60 mayperiodically revise or modify the default charging scheme based onhistorical data. For example, knowing that a particular bus can travel acertain distance between charges (based on historic miles/KWhr data),the control system 60 may adjust the default charging schedule of thebus to minimize energy consumption cost.

The control system 60 may receive data from and send instructions to thebuses 10 and/or the charging stations 30 in geographic area 100. FIG. 2Billustrates the data received by and the instructions send by controlsystem 60. Each electric bus 10 operating in the geographic area 100 maytransmit data 12 to the control system 60. And, each charging station 30in the geographic area 100 may transmit data 32 to the control system60. A bus 10 may send data 12 to the control system 60 wirelessly orthrough a wired connection. In some embodiments, a bus 10 may wirelesslytransmit data 12 periodically. In some embodiments, the bus 10 maytransmit to and/or receive data from the control system 60 when it dockswith a charging station 30. The data 12 transmitted by a bus 10 mayinclude, among others, identifying information of the bus 10 and driver,current state of charge (SOC) of the bus 10, the route 20 of the bus 10,the state of auxiliary charging unit (if any) on the bus 10, and thecurrent location of the bus 10. The SOC of the bus 10 may indicate theavailable charge (50% of full charge, etc.) on the bus 10 at anyparticular time. Based on this data 12 and stored data 62, the controlsystem 60 may estimate the SOC of the bus 10 when it reaches the nextcharging station 30 along its route. Data 12 may also include thecurrent operating parameters (such as, speed, load, etc.) of the bus 10.Based on the operating parameter data, the control system 60 maydetermine the rate of energy consumption of the bus 10 to get a betterestimate of the SOC when the bus 10 reaches the next charging station30.

Control system 60 may also transmit instructions 14 to the bus 10. Theseinstructions 14 may include, for example, the amount of time to chargeat a charging station 30, the amount of energy to recharge, the chargingstation 30 to charge at, etc. In some embodiments, instructions 14 mayalso include instructions to skip a charging event, delay charging untilafter a certain time, or to proceed to a different charging station 30in the same or a different route 20. These instructions 14 may alsoinclude suggested operating parameters (such as, speed, etc.) toconserve energy to extend the range of the bus 10. In some applications,the control system 60 may also reroute a bus 10 to a charging station 30that is not along its normal route 20.

The data 32 transmitted from the charging stations 30 may includedetails of charging of a bus 10. These details may include, for example,identification of the bus 10 that is being charged, the time ofcharging, amount of power transferred to the bus 10, amount of time ittook to transfer the power, rate of charging, etc. Data 32 from chargingstations 30 may also include information concerning the energy storagedevice 35, such as, the state of charge of the energy storage device 35.In some embodiments, the data may be transmitted real time, while inother embodiments, the data may be transmitted only periodically.

The control system 60 may also transmit instructions 34 to the chargingstations 30. These instructions 34 may include the amount of energy totransfer to a bus 10, and the rate of energy transfer. For instance, toreduce the total amount of energy consumed in a time window, the controlsystem 60 may send instructions 34 to the charging station 30 (and/or tothe bus 10) to delay charging a bus 10, to decrease the rate of energytransfer, or to charge a bus 10 using the energy storage system 35associated with the charging station 30. Charging a bus 10 using theenergy storage system 35 may avoid increasing the total rate of energyconsumption. Further, since energy is stored in the energy storagesystem 35 at times of lower energy cost, charging a bus 10 at times ofhigher energy cost using this lower cost stored energy may reduce thetotal energy cost. In some embodiments, the control system 60 mayinstruct a charging station 30 not to charge a because another bus thatis coming to charge may need recharging more critically.

The utility company 40 may update the control system 60 with data 42related to revised tariff schedules and energy costs. This data 42 maybe communicated to control system 60 wirelessly, or over a wirednetwork. It is also contemplated that this data 42 is manually inputinto the control system 60 from a tariff schedule or other costinformation mailed to authority 50.

In some embodiment, control system 60 may also receive information suchas traffic information and weather information. This information may bereceived from any source. In some embodiments, the buses 10 may providedata related to the weather and/or traffic to the control system 60. Insome embodiments, the control system 60 may receive weather related datafrom the weather bureau and traffic related data from the Department ofTransportation. It is also contemplated that, the control system 60 mayreceive weather and/or traffic information from private aggregators thatprovide live traffic and/or weather updates. The control system 60 maymodify the default charging schedule based on the weather and/or trafficdata.

FIG. 3A is a flow chart that illustrates an exemplary operation 200 ofcontrol system 60. The control system 60 may receive data 12 frommultiple (or in some embodiments, all) buses 10 operating in ageographic area 100 and data 32 from multiple charging stations 30 inthe geographic area 100 (step 210). Based on this data 12, 32 (and theprevailing tariff schedule), the control system 60 may develop acharging scheme for the buses 10 to reduce total energy cost (step 220).The control system 60 may then send instructions 14, 34 to the buses 10and/or the charging stations 30 to charge the buses 10 in a manner thatreduces total energy cost without sacrificing operational reliability(step 220). For example, in some geographic areas 100, the cost per unitof energy is lower (for e.g., $0.1) when the rate of energy consumption(typically measured as the total energy consumption within a fixed timeperiod, for e.g., 15 minutes) is below a certain value, and higher (thatis, >$0.1) when the rate of energy consumption is above this value. Insome geographic areas 100, the peak rate of energy consumption in abilling cycle may be used to calculate the total energy cost for theentire billing cycle. For example, if once during the billing cycle, therate of energy consumption was 3 times the average rate for the rest ofthe billing cycle (for example, multiple buses charging within a 15minute time window), the total energy cost for the entire billing cyclemay be calculated at a higher rate. In such circumstances, the controlsystem 60 may instruct the buses 10 to stagger their charging times sothat multiple buses 10 do not charge at the same fifteen minute timewindow and increase the rate of energy consumption and total energycost.

In some embodiments, the control system 60 may keep track of the energyconsumption of the charging stations 30 in the geographic area 100. And,based on the received and stored data 12, 32, and 62, the control system60 may determine the SOC of each bus 10 and the charging stations 30each bus 10 has access to. The control system 60 may then sendinstructions 14, 34 to the buses 10 and/or the charging stations 30 tocharge the buses 10 in a manner such that the overall energy cost isreduced. For example, at times of high energy cost, the control system60 may determine if the charging of a bus 10 can be delayed to a time oflower energy cost without sacrificing operational efficiency. If it can,the control system 60 may instruct one or more buses 10 to cancel (ordelay) a scheduled charging event and continue along its route 20 to thenext charging station 30. In some embodiments, the instructions 14 fromthe control system 60 to the buses 10 may also include operatingparameters to extend the range of the buses 10. In some embodiments, thecontrol system 60 may reroute a bus 10 to a charging station 30 that isnot along its normal route 20 if the available charge on the bus 10 isnot sufficient to safely reach the next charging station 30 along itsnormal route 20.

In some embodiments, the SOC of multiple buses 10 may be such that themultiple buses 10 may need to charge at substantially the same time (forexample, when their charging times are separated by less than or equalto 15 minutes). In some such embodiments, the control system 60 mayinstruct some of the buses 10 to proceed with charging as usual, andinstruct one or more charging stations 30 to use their associated energystorage devices 35 to provide at least a portion of the energy to chargethe buses 10. Since charging a bus 10 using an energy storage device 35does not immediately draw energy from the electric grid, the rate ofenergy consumption may be lower. In some embodiments, the instructionsto the charging station 30 may include directives to charge a percentageof the total energy from the energy storage device 35 and the remainderfrom the electric grid.

In some embodiments, the control system 60 may send instructions 14, 34to the buses 10 and the charging stations 30 based on real-time data 12,34 from the buses 10 and/or the charging station 30. In someembodiments, based on periodic data 12, 34 from the buses 10 and thecharging stations 30, the control system 60 may develop a chargingschedule for the buses 10 operating in the geographic area 100. Thecharging schedule may indicate when (time, etc.), where (chargingstation location, etc.), and the amount of energy each bus 10 in thefleet may charge. The control system 60 may then periodically revise thecharging schedule based on received data 12, 34.

FIG. 3B is a flow chart that illustrates another exemplary operation 300of control system 60. The control system 60 may receive data 12, 32 fromthe buses 10 and charging stations 30 in the geographic area 100 (step310). The control system 60 may include a default charging scheme forthe buses 10 as stored data 62 therein. Based on the received and thestored data, the controls system 60 may determine if the defaultcharging scheme for a bus 10 can be modified (step 320). That is, thecontrol system 60 may determine if there is any opportunity in reducingenergy cost by modifying the charging scheme. For instance, if the SOCof a bus 10 and/or the distance to the next charging station 30 is suchthat a charging event for the bus 10 cannot be postponed, control system50 may decide that the default charging scheme of this bus 10 cannot bemodified. If the default charging scheme cannot be modified (NO on step320), the control system 60 may send instructions 14, 34 to the bus 10and/or the charging station 30 to charge the bus 10 based on the defaultcharging scheme (step 340).

If the default charging scheme can be modified (YES on step 320), thecontrol system 60 may then determine if modifying the charging schemewill reduce cost (step 330). That is, the control system 60 maydetermine if the tariff schedule at that time is such that cost may bereduced by modifying the charging scheme of a bus 10. If cost can bereduced (YES on step 330), the control system 60 may modify the defaultcharging scheme of the bus 10 to reduce cost (step 350), and sendinstructions consistent with the modified charging scheme to the bus 1010 and/or the charging stations 30 (step 360). If modifying the chargingscheme will not provide sufficient cost savings (NO on step 330), thecontrol system 60 may send instructions 14, 34 based on the defaultcharging scheme (step 340).

In some embodiments, to determine if modifying the charging scheme willreduce cost (step 330), the control system 60 may first develop multiplepossible charging options based on the conditions at the time (forexample, the SOC of the bus, the tariff schedule, etc.), and thendetermine if implementing any of these multiple charging options willreduce cost. If cost can be reduced (YES on step 330), the controlsystem 60 may modify the default charging scheme with the option thatprovides the most reduction in cost (step 350).

While principles of the present disclosure are described with referenceto a fleet of electric buses, it should be understood that thedisclosure is not limited thereto. Rather, the systems and methodsdescribed herein may be employed to manage recharging of any electricvehicle. Those having ordinary skill in the art and access to theteachings provided herein will recognize additional modifications,applications, embodiments, and substitution of equivalents all fallwithin the scope of the embodiments described herein. Accordingly, theinvention is not to be considered as limited by the foregoingdescription. For example, while certain features have been described inconnection with various embodiments, it is to be understood that anyfeature described in conjunction with any embodiment disclosed hereinmay be used with any other embodiment disclosed herein.

We claim:
 1. A method for charging an electric vehicle of an electricvehicle fleet, comprising: receiving, at a control system, data frommultiple electric vehicles of the electric vehicle fleet, wherein thedata is wirelessly transmitted from each electric vehicle of themultiple electric vehicles while in motion, the data including at least(a) a current location of the electric vehicle, and (b) a current stateof charge of the electric vehicle; and determining, at the controlsystem, based at least on the received data, (a) the state of charge ofa first electric vehicle of the multiple electric vehicles when thefirst electric vehicle arrives for charging, and (b) an amount of energyto transfer to the first electric vehicle during the charging, whereindetermining the amount of energy to transfer to the first electricvehicle includes determining the amount based on a total amount ofenergy that was previously transferred to the multiple electric vehiclesduring a time window.
 2. The method of claim 1, wherein the determiningfurther includes estimating a time at which the first electric vehiclewill arrive for charging.
 3. The method of claim 2, wherein thedetermining further includes estimating a rate of energy consumption ofthe first electric vehicle.
 4. The method of claim 1, wherein thedetermining further includes determining a rate of energy transfer tothe first electric vehicle during the charging.
 5. The method of claim1, wherein determining the amount of energy to transfer to the firstelectric vehicle includes determining the amount based on a cost ofenergy when the first electric vehicle is being charged.
 6. The methodof claim 1, wherein the data wirelessly transmitted from each electricvehicle of the multiple electric vehicles further includes a speed ofthe electric vehicle.
 7. The method of claim 1, wherein the datawirelessly transmitted from each electric vehicle of the multipleelectric vehicles further includes identification information of theelectric vehicle.
 8. The method of claim 1, wherein determining theamount of energy to transfer to the first electric vehicle includesselecting an amount of energy less than the amount needed to fullycharge the first electric vehicle.
 9. A method for charging an electricvehicle of an electric vehicle fleet, comprising: receiving, at acontrol system, a tariff schedule, wherein the tariff schedule indicatesa cost of energy at different times; receiving, at the control system,data from multiple electric vehicles of the electric vehicle fleet,wherein the data is wirelessly transmitted from each electric vehicle ofthe multiple electric vehicles while in motion, the data from eachelectric vehicle including at least (a) information indicative of acharging schedule of the electric vehicle and (b) a current state ofcharge of the electric vehicle; and determining, at the control system,an amount of energy to transfer to a first electric vehicle of themultiple electric vehicles during charging based at least on (i) thestate of charge of each electric vehicle of the multiple electricvehicles and (ii) the tariff schedule.
 10. The method of claim 9,wherein the data from each electric vehicle further includes a currentlocation of the electric vehicle, and wherein the determining furtherincludes estimating a state of charge of the first electric vehicle whenit arrives for charging.
 11. The method of claim 10, further includingcalculating a total amount of energy that was previously transferred tothe multiple electric vehicles in a time window.
 12. The method of claim11, wherein the determining further includes determining a rate ofenergy transfer to the first electric vehicle during the charging basedon the calculated total amount of energy.
 13. The method of claim 10,wherein determining the amount of energy to transfer to the firstelectric vehicle includes selecting an amount of energy less than theamount needed to fully charge the first electric vehicle.
 14. The methodof claim 10, wherein determining the amount of energy to transfer to thefirst electric vehicle is further based on information related to asubsequent charging event.
 15. A control system for controlling thecharging of an electric vehicle fleet, comprising: a receiver configuredto receive data from multiple electric vehicles of the electric vehiclefleet, wherein the data is wirelessly transmitted from each electricvehicle of the multiple electric vehicles while in motion, the dataincluding at least (a) a current location of the electric vehicle, and(b) a current state of charge of the electric vehicle; receiving datafrom one or more charging stations, wherein the data from each of theone or more charging stations includes at least a current state ofcharge of an associated energy storage device; and a processorconfigured to determine, based at least on the received data from themultiple electric vehicles and the one or more charging stations, (a)the state of charge of a first electric vehicle of the multiple electricvehicles when the first electric vehicle arrives for charging, and (b)an amount of energy to transfer to the first electric vehicle during thecharging.
 16. The control system of claim 15, wherein the processor isfurther configured to estimate a time at which the first electricvehicle will arrive for charging.
 17. The control system of claim 15,wherein the processor is further configured to determine a rate ofenergy transfer to the first electric vehicle during the charging. 18.The control system of claim 15, wherein the processor is configured todetermine the amount of energy to transfer to the first electric vehiclebased additionally on a total amount of energy that was previouslytransferred to the multiple electric vehicles during a time window. 19.The control system of claim 15, wherein the processor is configured todetermine the amount of energy to transfer to the first electric as anamount less than the amount needed to fully charge the first electricvehicle.